Electric starting motor for internal-combustion engines



F. MNz

ELECTRIC STARTING MOTOR FOR INTERNAL COMBUSTION ENGINESl May 13 194241 Filed Feb. 24. 1923 Patented May 13, 1924.

UNITED STATES FRIEDRICH MNZ, OF STUTTGART, GERMANY.

ELECTRIC STARTING MOTOR FOR INTERNAL-COMBUSTION ENGINES.

Application filed February 24, 1923. Serial No. 621,032.

T0 all whom t may concern.:

Be it known that I, FRiEDRioH MNZ, a citizen of Germany, residing at Stuttgart, Germany, have invented certain new and useful Improvements in Electric Starting Motors for Internal-Combustion Engines (for which I have applied for a patent in Germany on Nov. 18, 1921, and Nov, 24, 1922), of which the following is a specification.

This invention relates to electric starting motors of the kind used in connection with explosion engines, and more particularly to the means for coupling the starting motor with the fly-wheel of the explosion engine for the purpose of starting the latter.

The object of the invention is to provide a means or device of the kind above indicated which will be of simple construction and absolutely reliable as regards its operation.

Further objects and advantages of the invention will be set forth in the detailed description which now follows:

In the accompanying drawing: Figure 1 is a longitudinal sectional view of the coupling device showing the adjacent partsof the starting motor and of the driven engine with the coupling members in disconnected position; Figure 2 is a sectional view of a modified construction of the coupling device.

Referring to the drawing in detail. and more particularly to Figure 1, the letter a designates the armature shaft of an electric motor having one end of hollow form. A pinion c and threaded spindle b are made in one piece so as to form an integral unit adapted to engage in and move lengthwise through a nut z' inserted in the hollow shaft a and rigidly connected therewith, whereby the pinion c is moved into and out of mesh with the gear teeth of a fly wheel g. A strong spring d and a light spring are also encased in the hollow shaft and are confined between a flange o on the spindle b and the nut 1I whereby to normally retain the spindle b in its retracted position. As shown in the drawing the spring d is fully extended and the spring f is partially extended whereby the initial movement of the spindle b is only opposed by the tension of the small or supplen'iental spring f.

The arrangement shown in Fig. 2 is substantially the same as that shown in Fig. 1 except that the springs l and f are confined between the spindle flange o and the hollow end of the shaft a whereby the spindle is normally maintained in outwardly projected position and is adapted to be moved inwardly incident to turning move` ment of the motor shaft a to engage the pinion c with the teeth of the fly wheel g, the latter occupying a position intermediate the pinion c and the end of the shaft a..

The nut z' is detachably connected with the hollow shaft .by a screw i0 so as to be interchangeable. Thus nuts having a righthand thread or a left-hand-thread may be employed as required. A disk or ring lc made of resilient material may be inserted in the hollow shaft and, as in Fig. 1, is confined between the flange 0v and the shaft a or, asin Fig. 2, between said flange and the 4nut t', the said disk or ring 7c serving the purpose of absorbing the shocks from the spindle ZJ vreturning the pinion c to its normal position. i

Theoperation is as follows: On starting the electric motor to full speed the armature shaft a is given so high a circumferential velocity that the pinion c and spindle b will be forcibly projected, owing to their inertia, the pinion c moving towards the flywheel g. As both the teeth of the pinion c and the teeth of the fly-wheel g are cut away and curved or rounded at their engaging ends, and as the light spring f only opposes the initial movement of the pinion c, the latter at once engages in the toothed rim of the fly-wheel to such extent that no injury is done to the cooperating teeth and their edges are not damaged.

Owing to the stopping or retardation of the fly-wheel and the spindle due to compression of the explosion engine the motor shaft a turns relative to the spindle and the nut z' acting on the thread of said spindlel will cause the spring d to be fully com pressed so that a complete and smooth engagement between the pinion and the iiywheel occurs.

Then the explosion engine starts running, the fly-wheel runs ahead of the rotary speed of the starting motor, whereby the pinion will be compelled, botli by the pressure of the re-acting spring' d and by the rotary power acting in opposite direction to disengage from the fly-wheel and to return into its initial or normal position shown in the drawing.

From the foregoing description, it will be seen that simple and efficient means are herein provided for accomplishiilng the objects of the invention, but while the elements shown and described` are, well adapted to serve the purposes for which they are intended, it is to be understood, that the invention is not limited to the precise construction sot forth, but inclu-des within its purview such changes as may be made within the spirit and scopeA of the appended claims;

Tha/t I claim is:

l; A mean-s for coupling anelectric= start-- ing motor with an explosion engine, comprising a motor shaft,A havinga hollow end, a nut removably mounted in said hollow end,. a thread-ed spindle engaging in said'l nut, api-'nien .rigidly connected.: with thev spindle, and a= spring within the hollow shaft end acting tov hold the pinion in its normal positionv and adapted to .be coinpressed when the said spindle with the pinion thereon moves; in one direction.

2; A means for coupling any electric starting motor with an explosion engine, comprifsingv amotor shaft having a hollowr end, a nut detachably affixed within. saidV hollow end, a threaded spindleengagingin said nut, a pinion rigidly connected with the spindle, and a spring, within the hollow shaft.,

A, means for coupling an electric starting motor with an explosion engine' coinprising aY motory shaft having a. hollow end, a nut detachably affixed within said hollow nut, a pinion rigidly connected with the spindle, a spring; within the hollofw shaft end., and a circular member made ofi resilient material andi embedded inthe'hollow shaft end. c Y

5. A means forcoupling an electric starting motor with an explosion engineycomprising a motor shaft having' a hollow end, a nut reniovab'lyv mounted within said hollow shaft end, means detachably securing saidnut in position, a screw-spindle engaging in saidV nut',l a pinion rigidly` connected with the spindle.. a Vstrong spring and alight spring both housed within; the hollow shaft end, and a circula-r member made of resilient material alnd embedded in end. t

In testimony whereof I affix my signature in presence of two witnesses;

FRIEDRICH MNZ.

VVi-tnessesz AUGUST; DInTERicH', OTTO WAGNER.V

the hollow shaft 

